The long term goal of this study is to determine if and how neoplastic progression can be interrupted by immunization with monclonal anti-idiotypic antibodies that resemble (R) the antigenic structures (epitopes-E) on preneoplastic and/or neoplastic mammary lesions -monoclonal anti-Id(RE). The test system is the transplantable, preneoplastic, hyperplastic alveolar nodule (HAN) lines and the tumors which develop spontaneously from them in strain BALB/c mice. The specific aims are: 1) prepare monoclonal, anti-idiotypic antibodies against monoclonal antibodies (MoAbs) directed to HANs and/or their sponstaneous tumors; 2) select monoclonal anti-Ids that resemble the mammary lesion epitopes and determine their immunogenicity; 3) determine the growth and tumorigenicity of HANs and tumors in mice immunized with monoclonal anti-Id(RE). The questions we wish to address are whether immunization with anti-idiotype antibodies is an effective way of stimulating lymphocytes, and if so, whether the results will be modulation of neoplastic progression. The otucome of our studies is important to furthering our understanding of the mechanisms of progression and to pointing to a possible direction for immunoprevention of cancer.